How finicky are the Lionel Santa and Snowman chase boxcars

I've had one for years and it's my favorite Christmas car. The height of the plastic frame on top of the boxcar is adjustable so you should be good to go. You probably could use a drop of blue locktite on the screw threads when you get it to the correct height to prevent it from vibrating loose and causing a failure.

For a long time I wouldn't have considered those cars, as the superstructure coming up from the boxcar roof just bugged me visually. Then I saw one of David from Dearborn videos showing these cars in operation. I changed my mind.

So now I have two of them and love the continual operation activity, regardless of their lack of realism. You do need to fiddle with the height of the superstructure on the boxcar roof. There are two screws, and with one of the figures on top, you roll it up to the trackside tower, and adjust the screws so that the base that the figures are mounted to, slides into the trackside tower as smoothly as possible.

I've found once you get them adjusted, they are for the most part, quite reliable. Once in a blue moon, one of the figures won't quite line up to the trackside tower and will fall off the train car. I have mine set up at the front of the layout so it makes correcting this mistake quite easy. As well as making adjustments to the height on the train car.

One problem you could run into though, is the clearance for other train cars. I'm using 027 track. I just went and made a measurement: It is 4-7/8 inches from the bottom of the trackside tower (my layout surface) to the bottom of the structure that overhangs the track. A double stack trailer car will not clear. And my Bugs Bunny/Yosemite Same car (mid 1990's vintage) - depending on at what point Bugs raises to full height, his rabbit ears will rub against the bottom of the overhang.

So if you're running any sort of scale height cars - or anything taller - you might want to have this device on a dedicated separate line of track where you will run shorter height rolling stock... providing you have separate loops of track.

I've not tried this, but you might be able to cob another way of mounting the trackside structure to the layout surface, using a scrap piece of wood to raise the height 1/4 of an inch. The height of the superstructure coming from the boxcar is adjustable, but I've never tried to see just how high I could raise it. It's just guess that you could raise it a quarter of an inch. I'm also running the true 027 version of this car. I know Lionel also at one time made one with a standard 6464 sized box car... a C&O if memory serves me right. And those cars are a hair taller than the 027 type.